ABSTRACT
One advantage of basing everything on thermodynamics is that there is no need to make assumptions about mercury in a mercury thermometer, platinum in a resis tance thermometer or any other substance. Each of these, if assumed to vary linearly with temperature, would define its own temperature scale. This is an altogether dif ferent thing from the Celsius and Fahrenheit scales; these just involve shifting the zero of the absolute scale or changing the temperature interval belonging to one degree or both.
